Surface modification agents for lithium batteries

ABSTRACT

An active material for an electrochemical device wherein a surface of the active material is modified by a surface modification agent, wherein the surface modification agent is an organometallic compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/546,440, filed on Jul. 11, 2012, now U.S. Pat. No. 9,065,115, whichis a continuation of U.S. patent application Ser. No. 13/397,319, filedon Feb. 15, 2012, now U.S. Pat. No. 8,292,974, which is a continuationof U.S. patent application Ser. No. 12/454,173, filed on May 13, 2009,now U.S. Pat. No. 8,187,746, which in turn claims the benefit of U.S.Provisional Application No. 61/127,901, filed May 16, 2008, all of whichare incorporated herein by reference, in their entireties, for any andall purposes.

GOVERNMENT RIGHTS

The United States Government has rights in this invention pursuant toContract No. W-31-109-ENG-38 between the United States Government andThe University of Chicago and/or pursuant to Contract No.DE-AC02-06CH11357 between the United States Government and UChicagoArgonne, LLC representing Argonne National Laboratory.

FIELD

The present invention generally relates to lithium rechargeablebatteries. More particularly, surface modification agents for electrodesare described.

BACKGROUND

There has been growing interest in developing safe, high-power lithiumion batteries for transportation applications, such as hybrid electricvehicles (HEV) and plug-in hybrid electric vehicles (PHEV). Among theavailable portable energy storage solutions, lithium ion batteries havethe highest energy density, and as a result, lithium ion batteries are alikely candidate for use in transportation applications. Yet, there aretechnical barriers for using lithium ion batteries in such applications.

Technological barriers related to the use of lithium ion batteries,include power capability concerns. As batteries decrease in size andcost, the power capability of the batteries must remain high. In otherwords, for a battery to find application as a transportation powersource, the battery needs to exhibit a enough power capability to powerthe vehicles or accept energy from braking vehicles.

A certain amount of gas is generated inside a battery due to theinterfacial reactions inside a lithium ion battery, such as formation ofsolid electrolyte interphases (SEI) during formation or decomposition ofold SEI layers at elevated temperatures. The generation of gas may leadto a slow degradation of electrode materials, or a reduction in theactive electrochemical surface area (i.e., an increase in impedance) byblocking the charge/ion transport pathways. When gas accumulates in abattery cell, the power capability of the cell is then concomitantlydeteriorated. Nano-structured Li₄Ti₅O₁₂ can be a safe negative electrodematerial with high power capability and capacity retention. However,significant amount of gas is observed at elevated temperatures whennano-structured Li₄Ti₅O₄ was used against lithium manganese oxidespinels.

SUMMARY

In one aspect, an active material for an electrochemical device having asurface modification agent is provided. In some embodiments, the surfacemodification agent is a silane, organometallic compound, or a mixture oftwo or more thereof.

In other embodiments, the surface modification agent is a silane, andthe silane has Formula I, II, III, IV, or a mixture of any two or morethereof:

wherein:

-   -   X¹, X², X³ and X⁴ are independently —Cl, —Br or alkoxyl groups;    -   R¹, R², and R³ are independently a halogen, a substituted or        unsubstituted alkyl group, a substituted or unsubstituted aryl        group, an OR⁵ group, or a group of Formula V; and    -   R⁵ is a substituted or unsubstituted alkyl group, or a        substituted or unsubstituted aryl group. In some such        embodiments, at least one of substitution groups R¹, R², and R³        is a substituted alkyl group that is an ethylene oxide moiety of        Formula VI:

wherein:

-   -   m is an integer from 0 to 10;    -   n is an integer from 1 to 10; and    -   R⁶ is a substituted or unsubstituted alkyl group, a substituted        or unsubstituted aryl group, or a carbonate-based sub group of        Formula VII:

-   -   wherein        -   R⁷ is hydrogen, a substituted or unsubstituted alkyl group            having from 1 to 12 carbon atoms; a substituted or            unsubstituted alkenyl group having from 2 to 8 carbon atoms;            and        -   q is an integer from 0 to 8.

In other embodiments, the surface modification agent is a metalalkoxide, a metal halide, a metal alkyl, a metal alkylamide, a carbonylmetal compound, a metal aryl, a metal cyclopentadienyl, a phosphine, ametal phosphine, a metal hydride, or a mixture of any two or morethereof.

In some embodiments, the surface modification agent is an organometalliccompound of Formula VIII, Formula IX, or a mixture thereof:

wherein

-   -   Formula VIII is M-(R⁸)_(p);    -   Formula IX is M-(O—R⁹)_(p′);        -   wherein            -   M is a metal; and            -   R⁸ and R⁹ are each independently hydrogen, a halogen, an                substituted or unsubstituted alkoxide group, a                substituted or unsubstituted alkyl group, a substituted                or unsubstituted aryl group, a substituted or                unsubstituted aminealkyl group, and            -   p is an integer from 1 to 6.

In other embodiments, the surface modification agent is a compoundselected from the group consisting of aluminum sec-butoxide, aluminumtribromide, aluminum trichloride, diethylaluminum ethoxide,tris(ethylmethylamido)aluminum, triethylaluminum, triisobutylaluminum,trimethylaluminum, tris(diethylamido)aluminum,tris(ethylmethylamido)aluminum, trimethylarsine, diborane,trimethylboron, bis(N,N′-diisopropylacetaminato)cobalt(II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper(II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride, tungsten (VI) fluoride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III)butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide, and a mixture ofany two or more thereof.

In other embodiments, the surface modification agent is cyclic organiccompound that can under ring opening coupling reaction with acidicgroups like —OH; at least one of the chemical bonds in the cyclicorganic compound is sensitive to acidic groups; when reacting withacidic group, the ring will be opened at the specific site and undergocoupling reaction with the surface acidic group without forming residuechemicals. An exemplary of such surface modification agent is, but notlimited to, cyclic alkylene oxides and epoxy.

In other embodiments, the surface modification agent is a compoundselected from the group consisting of ammonia, phosphine, ahalophosphine, a alkylphosphine, a haloalkylphosphine, an alkylamine,and a mixture of any two or more thereof.

In some embodiments, the surface of the active material is alternatelytreated for 1 to 1000 times with a first and a second surfacemodification agents, where the first modification agent is selected fromthe group consisting of the organometallic compound of Formula VIII,Formula IX, aluminum sec-butoxide, aluminum tribromide, aluminumtrichloride, diethylaluminum ethoxide, tris(ethylmethylamido)aluminum,triethylaluminum, triisobutylaluminum, trimethylaluminum,tris(diethylamido)aluminum, tris(ethylmethylamido)aluminum,trimethylarsine, diborane, trimethylboron,bis(N,N′-diisopropylacetaminato)cobalt(II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper(II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride, tungsten (VI) fluoride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III)butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide, and a mixture ofany two or more thereof; and the second surface modification agent isselected from the group consisting of ammonia, phosphine, ahalophosphine, a alkylphosphine, a haloalkylphosphine, an alkylamine,and a mixture of any two or more thereof.

In another aspect, an electrode of the above active materials having asurface modification agent are provided. In some embodiments, theelectrode is a negative electrode. In other embodiments, the electrodeis a positive electrode.

In another aspect, methods of modifying the surface of an electrode orelectrode active material with a surface modification are provided. Insome embodiments, the methods include modifying the surface of anelectrode of a battery by providing a surface modification agent; andadding the surface modification agent to a non-aqueous electrolyte;wherein the battery comprises the electrode and the non-aqueouselectrolyte. In some such embodiments, a concentration of the surfacemodification agent in the non-aqueous electrolyte is from about 0.00001wt % to 10 wt %. In other embodiments, the concentration of the surfacemodification agent in the non-aqueous electrolyte is from about 0.0001wt % to 3 wt %. In still other embodiments, the concentration of thesurface modification agent in the non-aqueous electrolyte is from about0.001 wt % to 2 wt %.

In other embodiments, the methods include modifying the surface of anelectrode laminate by providing a gas phase surface modification agentor a solution of a surface modification agent; and exposing the surfacemodification agent to the electrode laminate; wherein the solution ofthe surface modification agent is prepared by dissolving or suspendingthe surface modification agent in a solvent. In some such embodiments,the time of the exposing step is from about 0.1 second to 24 hours. Inother embodiments, the time of the exposing step is from about 1 secondto 1 hour. In still other embodiments, the time of the exposing step isfrom about 1 second to 10 minutes.

In other embodiments, the methods include modifying the surface of anelectrode active material by providing a solution or a suspension of asurface modification agent; providing the electrode active material;preparing a slurry of the surface modification agent, the electrodeactive material, a polymeric binder, and a conductive filler; castingthe slurry in a metallic current collector; and drying the cast slurry.In some such embodiments, the drying step is carried out at atemperature between about 40° C. and 200° C. In other embodiments, thepolymeric binder is PVDF, PVDF-HFP, or a mixture thereof. In otherembodiments, the conductive filler is carbon black, carbon fiber,graphite, a metallic nano powder, or a mixture of any two or morethereof. In other embodiments, the concentration of the surfacemodification agent in the slurry is from about 0.00001 wt % to 5 wt %.In still other embodiments, the concentration of the surfacemodification agent in the slurry is from about 0.0001 wt % to 3 wt %. Instill other embodiments, the concentration of the surface modificationagent in the slurry is from about 0.001 wt % to 2 wt %.

In other embodiments, the methods include modifying the surface of anelectrode active material by providing a gas phase surface modificationagent or a solution of a surface modification agent; and exposing thesurface modification agent to the electrode active material; wherein theelectrode active material is in the form of a powder. In some suchembodiments, the time of the exposing step is from about 0.1 second to24 hours. In other embodiments, the method further includes providingsteam or water in addition to the surface modification agent. In stillother embodiments, the method further comprises exposing the surfacemodification agent and moisture, alternately, to the electrode laminateor the electrode active material a repeat number of times from 1 to1000. In some embodiments, the repeat number of times is from 3 to 100.In other embodiments, the repeat number of times is from 5 to 20. In yetother embodiments, the exposing surface modification agent is performedby alternately exposing two or more surface modification agents.

In other embodiments, the methods include modifying the surface of anelectrode active material by providing a gas surface modification agent;providing a radiofrequency discharge to create a plasma of the gassurface modification agent; and contacting the gas surface modificationagent with the electrode active material. In some such embodiments, thegas surface modification agent is a fluorine-based gas F₂,C_(q″)F_(2q″+2), C_(q″)F_(2q″), or C_(q″)F_(2q″−2) and q″ is an integerranging from 1 to 20. In some embodiments, the fluorine-based gas isCF₄. In other embodiments, a pressure of the gas surface modificationagent is less than 10 Pa. In other embodiments, the gas surfacemodification agent is a mixture of CF₄ and an inert gas selected fromnitrogen, helium, argon, or a mixture of any two or more thereof. Insome embodiments, a concentration of CF₄ in the inert gas is less thanabout 20%.

In some embodiments, any of the above active materials is a positiveelectrode active material selected from the group consisting of spinel,olivine, carbon-coated olivine, LiFePO₄, Li_(x′)M′_(y), M″_(z)′PO₄,Li_(1+x″)Ni_(α)Mn_(β)Co_(γ)Met′_(δ)O_(2−z″)F_(z″), A_(n″)B₂(XO₄)₃,vanadium oxide, and mixtures of any two or more thereof; and furtherwherein

-   -   M′ is selected from the group consisting of V, Cr, Mg, Fe, Co,        and Ni;    -   M″ is selected from group consisting of IIA, IIIA, IVA, VA, VIA        and IIIB metals having an ionic radius less than the ionic        radius of Fe²⁺;    -   Met′ is selected from the group consisting of Mg, Zn, Al, Ga, B,        Zr, and Ti; and    -   0≦x′≦1, 0≦y′≦1, 0≦z′≦1, 0≦x″≦0.4, 0≦α≦1, 0≦β≦1, 0≦γ≦2, 0≦δ≦0.2,        0≦z″≦0.5, and 0≦n″≦3.

In some such embodiments, the positive electrode material is coated withAl₂O₃, AlF₃, ZrO₂, SiO₂, MgO, TiO₂, CaO, SnO₂, WO₃, In₂O₃, Ga₂O₃, Sc₂O₃,Y₂O₃, La₂O₃, HfO₂, V₂O₅, Nb₂O₅, Ta₂O₅, MnO, MnO₂, CoO, Co₂O₃, NiO, NiO₂,CuO, ZnO, MgF₂, CaF₂, Mo, Ta, W, Fe, Co, Cu, Ru, Pa, Pt, Al, Si, Se,oxyfluorides, or a mixture of two or more of thereof.

In some embodiments, any of the above active materials is a negativeelectrode material selected from the group consisting of graphite,amorphous carbon, Li₄Ti₅O₁₂,

M_(1−x)A_(x)Li_(2−y)B_(y)Ti_(6−z)C_(z)O_(14−t)Q_(t), tin alloys, siliconalloys, intermetallic compounds, lithium metal, or mixtures of any twoor more such materials; and further wherein:

-   -   M is selected from the group consisting of Ba, Sr, Ca, Mg, Pb,        and Sn;    -   0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦t≦0.5;    -   each of A, B and C are independently at least one divalent,        trivalent or tetravalent metal; and    -   Q is a monovalent or divalent anion.

In some such embodiments, the negative electrode material is coated withAl₂O₃, AlF₃, ZrO₂, SiO₂, MgO, TiO₂, CaO, SnO₂, WO₃, In₂O₃, Ga₂O₃, Sc₂O₃,Y₂O₃, La₂O₃, HfO₂, V₂O₅, Nb₂O₅, Ta₂O₅, MnO, MnO₂, CoO, Co₂O₃, NiO, NiO₂,CuO, ZnO, MgF₂, CaF₂, Mo, Ta, W, Fe, Co, Cu, Ru, Pa, Pt, Al, Si, Se,oxyfluorides or a mixture of two or more of thereof.

In another aspect, an electrochemical device is provided having apositive electrode; a negative electrode; and a non-aqueous electrolyte;wherein the negative electrode and/or the positive electrode comprises asurface modification agent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a composite illustration of a composite photograph of batterycells without (A) and with (B) added surface modification agent. A freshcell (C) after sealing, but before any electrochemical testing isconducted is also included.

DETAILED DESCRIPTION

Surface Modification Agents

In various aspects, surface modified active materials, surfacemodification agents and methods to of modifying materials that are usedin lithium ion batteries, to suppress gas release from the batteries,are provided. Such surface modification agents include a class ofcompounds that may selectively react with acidic functional groups onthe surface of a material used to manufacture battery electrodes, and toeliminate the chemical or electrochemical reactivity of such functionalgroups. While any electrode may be suitable for modification, in someembodiments, the electrode is an electrode laminate as are known tothose of skill in the art. Such acidic functional groups include, butare not limited to, —OH and —COOH. As used herein, a “laminate”electrode is an electrode constructed from an electrode active material,a conductive filler, and a polymeric binder that maintains the physicalintegrity of the electrode.

In general, the surface modification agents are a group of compoundsthat can selectively react with surface functional groups on the activematerials that form electrodes. In some embodiments, the surfacemodification agent is one or more silanes of the formulas represented asFormula I, II, III, IV, and V.

wherein X¹, X², X³ and X⁴ are independently —Cl, —Br or alkoxyl groups;R¹, R², and R³ are independently a halogen, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aryl group, anOR⁵ group, or a group of Formula V; and R⁵ is a substituted orunsubstituted alkyl group, or a substituted or unsubstituted aryl group.In some embodiments, the alkyl or aryl groups are substituted with oneor more halogens. In some other embodiments, at least one ofsubstitution group of R¹, R², or R³ contains an ethylene oxide moiety asshown in Formula VI:

where, m is an integer from 0 to 10; n is an integer from 1 to 10; andR⁶ is a substituted or unsubstituted alkyl group, a substituted orunsubstituted aryl group, or a carbonate-based sub group. In someembodiments, the alkyl or aryl groups are substituted with one or morehalogens. Exemplary carbonate-based subgroups in those represented byFormula VII:

where R⁷ is hydrogen, or a group selected from a substituted orunsubstituted alkyl group have from 1 to 12 carbon atoms, a substitutedor unsubstituted alkenyl group having from 2 to 8 carbon atoms; and q isan integer from 0 to 8.

In other embodiments, the surface modification agent is anorganometallic compound of Formula VIII or IX, where the compound ofFormula VIII is M-(R⁸)_(p) and the compound of Formula IX isM-(O—R⁹)_(p′). In such other embodiments, M is a metal; each R⁸ and R⁹are independently hydrogen, a halogen, an alkoxide group, a substitutedor unsubstituted alkyl group, a substituted or unsubstituted aryl group,or an alkylamine group; and p is an integer from 1 to 6. In someembodiments, the alkyl or aryl groups are substituted with one or morehalogens.

Suitable organometallic compounds of Formulas VIII and IX include, butare not limited to, metal alkoxides, metal halides, metal alkyls, metalalkylamides, carbonyl metal compounds, metal aryls, metalcyclopentadienides, phosphines, metal phosphines, metal hydrides, andthe like. For example, some compounds of Formula VIII and IX include,but are not limited to aluminum sec-butoxide, aluminum tribromide,aluminum trichloride, diethylaluminum ethoxide,tris(ethylmethylamido)aluminum, triethylaluminum, triisobutylaluminum,trimethylaluminum, tris(diethylamido)aluminum,tris(ethylmethylamido)aluminum, trimethylarsine, diborane,trimethylboron, bis(N,N′-diisopropylacetaminato)cobalt(II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper(II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride, tungsten (VI) fluoride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III)butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide. In yet otherembodiments, the surface modification agent is a compound such asammonia, phosphine, a halophosphine, a alkylphosphine, ahaloalkylphosphine, an alkylamine, or a mixture of any two or more suchcompounds.

Methods

In another aspect, methods of modifying the surface chemistry of activematerials for a lithium, or lithium ion battery are provided. There area number of methods in which the surface modification agent may beintroduced to the electrode, or active materials from which theelectrode is produced.

In such methods, surface modification agents may be introduced to abattery as an additive to non-aqueous electrolytes. In such embodiments,all the wettable surface area of an electrode by the electrolyte isexposed to the surface modification agent. Once exposed surfacefunctional groups on the electrodes can be modified by reaction with thesurface modification agent. By introducing the surface modificationagents to the battery through the electrolyte, negative and positiveelectrodes may be modified simultaneously. In some embodiments, theconcentration of the surface modification agent in the non-aqueouselectrolyte is from about 0.00001 wt % to 10 wt %, from about 0.0001 wt% to 3 wt %, in other embodiments, or from about 0.001 wt % to 2 wt %,in yet other embodiments.

Alternatively, surface modification agents may be directly applied tothe electrode by exposing the dry electrode to a gas phase, or dilutesolution, of the inventive surface modification agent. After theexposure, the electrode may be heated to remove residual surfacemodification agent.

In another alternative, surface modification agents may be introduceddirectly into an electrode slurry from which an electrode may beproduced. In such embodiments, the electrode slurry is a non-homogeneousmixture of an active positive or negative electrode material, aconductive filler, a polymeric binder, and a solvent. Such materials aretypically mixed and cast into electrodes. During the mixing and castingprocess, the surface modification agents react with surface functionalgroups, such as —OH and —COOH, on the active material's surface. Aftercasting, excess surface modification agent, and reaction byproducts areremoved during the drying process, while the reacted agent is chemicallybound to the surface of the electrode material, and is not removed bysimple heat treatment. Suitable conductive fillers for use in the slurryand electrode include, but are not limited to materials such as carbonblack, carbon fiber, graphite, or other metallic nanopowder materials.Suitable polymeric binders for use in the slurry and electrode include,but are not limited to polymers such as PVDF (polyvinylidenedifluoride), or co-polymers of PVDF with other materials such ashexafluoropropylene (PVdF-HFP).

In yet another alternative, surface modification agents may be directlyapplied to an active electrode material powder or electrode laminate byexposing the powder or laminate to the gas phase, or diluted solution ofthe surface modification agent. In some other embodiments, the activematerial powder is treated with the surface modification agent and wateror moisture to achieve multiple layer modification and to maximizecoverage. Still in some other embodiments, the active material powder istreated with more than one inventive surface modification agents as wellas water or moisture to introduce new functionalities and to maximizethe coverage. In some embodiments, the exposure time of the surfacemodification agent to the active electrode material is from about 0.1second to 24 hours, from about 1 second to 1 hour, in other embodiments,or from about 1 second to 10 minutes, in yet other embodiments.

In a further alternative, methods of surface modification of the abovematerials are provided and may be accomplished using a gas such as F₂,C_(q″)F_(2q″+2), C_(q″)F_(2q″), or C_(q″)F_(2q″−2) where q″ is aninteger ranging from 1 to 20, in a reactor with a radiofrequency (R_(f))discharge. For example, CF₄ is one such suitable gas. In general, insuch methods, the gas is used to make a plasma which, when in contactwith the active material, grafts fluorinated functionalities directly tothe material's surface. In the case of CF₄, the CF₄ plasma graftsfluorine atoms to the active material's surface by a mechanism thatinvolves CF_(q)-radical reactions at the surface as well, where q isfrom 1-4. As a general procedure, samples of an active material, such asLi₄Ti₅O₁₂, are placed in the center of a chamber where R_(f) dischargeoccurs using CF₄ gas. The flow rate of the CF₄ may be widely varied,depending upon the surface modification desired, but is typically on theorder of about 10 cm³/min. The total gas pressure is typically be lessthan about 10 Pa. In some examples, the power may range from about 20 Wto 300 W, but is typically about 80 W. The plasma frequency is typically13.56 MHz. Temperature may also impact the surface modification and thetemperature is typically less than about 150° C. The time of exposure ofthe material to the plasma is typically less than 2 hours. Substantialproduction of atomic fluorine after the dissociation CF₄ gas andimproved radical production efficiency can be obtained by adjusting theflow rate of the gas, the gas pressure, the temperature of the sample,and the time of exposure of the material to the plasma.

In other embodiments, the surface modification can be carried out bysurface fluorination where the material can be put in fluorine reactorand either fluorine gas or a mixture of fluorine gas and an inert gas isintroduced to the reactor to react with acidic groups at the surface ofthe active material. Inert gases may include helium, nitrogen, argon,and other such gases known to those of skill in the art. The temperatureof the reactor should not exceed 120° C. to prevent the decomposition ofthe electrode material. In the situation where only fluorine gas isused, the temperature of the reactor is typically less than 40° C., andthe time of fluorination is less than about 60 min. In the situationwhere the fluorination of the active material's surface is carried outusing a mixture of fluorine gas and an inert gas such nitrogen, argon,or other such inert gases, the concentration of fluorine gas in themixture is less than about 20%, and the temperature is less than about120° C. The fluorination could be static using a close reactor, or couldbe in a form of flowing the gas through the reactor.

In any of the above methods, the active material may be repeatedlycontacted with the surface modification agent, until the desired levelof modification is achieved. For example, after the first modificationof the active material, subsequent modifications may be iteratively madeon the material recovered from the previous iteration. For example, thesurface modification agent may be exposed to the electrode laminate orthe electrode active material a repeat number of times ranging from 1 to1000, or more. In some embodiments, the repeat number of times, oriterations, is from 3 to 100. In other embodiments, the repeat number oftimes, or iterations, is from 5 to 20.

In another aspect, and as described above, lithium batteries may beprepared using the surface modification agents. Typically, the batteriesinclude a positive electrode, a negative electrode, and a non-aqueouselectrolyte, and either one or both of the positive or negativeelectrode has been modified with a surface modification agent. The anodeand the cathode in lithium batteries are typically separated from eachother by a porous separator.

Suitable negative electrodes for lithium batteries include those havinggraphite, amorphous carbon, Li₄Ti₅O₁₂,M_(1−x)A_(x)Li_(2−y)B_(y)Ti_(6−z)C_(z)O_(14−t)Q_(t), tin alloys, siliconalloys, intermetallic compounds, lithium metal, or mixtures of any twoor more such materials. In such materials, M is selected from Ba, Sr,Ca, Mg, Pb, Sn and other divalent cations; 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5,0≦t≦0.5; each of A, B and C are independently at least one divalent,trivalent or tetravalent metal; and Q is a monovalent or divalent anion.Suitable graphitic materials include natural graphite, artificialgraphite, graphitized mesocarbon microbeads, and graphite fibers, aswell as other amorphous carbon materials. The negative electrode, or thematerial used to prepare the negative electrode may additionally becoated with a material such as Al₂O₃, AlF₃, ZrO₂, SiO₂, MgO, TiO₂, CaO,SnO₂, WO₃, In₂O₃, Ga₂O₃, Sc₂O₃, Y₂O₃, La₂O₃, HfO₂, V₂O₅, Nb₂O₅, Ta₂O₅,MnO, MnO₂, CoO, Co₂O₃, NiO, NiO₂, CuO, ZnO, MgF₂, CaF₂, Mo, Ta, W, Fe,Co, Cu, Ru, Pa, Pt, Al, Si, Se, oxyfluorides, or a mixture of two ormore of thereof.

Suitable positive electrodes for lithium batteries include those havingspinel, olivine, carbon-coated olivine, LiFePO₄,Li_(x″)M′_(y′)M″_(z″)PO₄,Li_(1+x″)Ni_(α)Mn_(β)Co_(γ)Met′_(δ)O_(2-z″)F_(z″), A_(n″)B₂(XO₄)₃(Nasicon), vanadium oxide, or mixtures of any two or more suchmaterials. In such materials, M′ is selected from V, Cr, Mg, Fe, Co, orNi; and M″ is selected from group IIA, IIIA, IVA, VA, VIA and IIIBmetals having an ionic radius less than the ionic radius of Fe²⁺. Insuch materials, Met′ is selected from Mg, Zn, Al, Ga, B, Zr, or Ti;0≦x′≦1, 0≦y′≦1, 0≦z′≦1, 0≦x″≦0.4, 0≦α≦1, 0≦β≦1, 0≦γ≦2, 0≦δ≦0.2,0≦z″≦0.5, and 0≦n″≦3. The positive electrode, or the material used toprepare the positive electrode may additionally be coated with amaterial such as Al₂O₃, AlF₃, ZrO₂, SiO₂, MgO, TiO₂, CaO, SnO₂, WO₃,In₂O₃, Ga₂O₃, Sc₂O₃, Y₂O₃, La₂O₃, HfO₂, V₂O₅, Nb₂O₅, Ta₂O₅, MnO, MnO₂,CoO, Co₂O₃, NiO, NiO₂, CuO, ZnO, MgF₂, CaF₂, Mo, Ta, W, Fe, Co, Cu, Ru,Pa, Pt, Al, Si, Se, oxyfluorides, or a mixture of two or more ofthereof.

Suitable non-aqueous electrolytes include an alkali metal salt dissolvedin a polar aprotic solvent. The alkali metal salt is typically presentat a concentration of from about 0.5 to about 2 molar and is typically alithium salt. Exemplary lithium salts include LiCF₃CO₂, LiC₂F₅CO₂,LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiPF₂(C₂O₄)₂, LiPF₄(C₂O₄), LiCF₃SO₃,LiN(CF₃SO₂)₂, LiC(CF₃SO₂)₃, LiN(SO₂C₂F₅)₂), lithium alkylfluorophosphates, lithium bis(oxalato)borate (LiBOB), LiBF₂(C₂O₄),Li₂B₁₂X_(12−n)H_(n), Li₂B₁₀X_(10−n′)H_(n′), and a mixture of any two ormore such materials, where X is selected from OH, OCH₃, F, Cl, Br, or I,n is an integer from 0 to 12, and n′ is an integer from 0 to 10.

In some embodiments, the non-aqueous electrolytes include and electrodestabilizing additive to protect the electrodes from degradation. Seee.g., co-pending U.S. application Ser. Nos. 10/857,365, 11/279,120, andprovisional application No. 60/647,361. Thus, electrolytes of theinvention can include an electrode stabilizing additive that can bereduced or polymerized on the surface of a negative electrode to form apassivation film on the surface of the negative electrode. Likewise,inventive electrolytes can include an electrode stabilizing additivethat can be oxidized or polymerized on the surface of the positiveelectrode to form a passivation film on the surface of the positiveelectrode. In some embodiments, electrolytes of the invention furtherinclude mixtures of the two types of electrode stabilizing additives.The additives are typically present at a concentration of about 0.001 to8 wt %.

In some embodiments, an electrode stabilizing additive is a substitutedor unsubstituted linear, branched or cyclic hydrocarbon comprising atleast one oxygen atom and at least one aryl, alkenyl or alkynyl group.The passivating film formed from such electrode stabilizing additivesmay also be formed from a substituted aryl compound or a substituted orunsubstituted heteroaryl compound where the additive comprises at leastone oxygen atom. Alternatively, a combination of two additives may beused. In some such embodiments, one additive is selective for forming apassivating film on the cathode to prevent leaching of metal ions andthe other additive can be selective for passivating the anode surface toprevent or lessen the reduction of metal ions at the anode.

Representative electrode stabilizing additives include 1,2-divinylfuroate, 1,3-butadiene carbonate, 1-vinylazetidin-2-one,1-vinylaziridin-2-one, 1-vinylpiperidin-2-one, 1 vinylpyrrolidin-2-one,2,4-divinyl-1,3-dioxane, 2 amino-3 vinylcyclohexanone,2-amino-3-vinylcyclopropanone, 2 amino-4-vinylcyclobutanone,2-amino-5-vinylcyclopentanone, 2-aryloxy-cyclopropanone,2-vinyl-[1,2]oxazetidine, 2 vinylaminocyclohexanol,2-vinylaminocyclopropanone, 2 vinyloxetane, 2-vinyloxy-cyclopropanone,3-(N-vinylamino)cyclohexanone, 3,5-divinyl furoate,3-vinylazetidin-2-one, 3 vinylaziridin 2 one, 3 vinylcyclobutanone, 3vinylcyclopentanone, 3 vinyloxaziridine, 3 vinyloxetane,3-vinylpyrrolidin-2-one, 4,4 divinyl-3 dioxolan 2-one, 4vinyltetrahydropyran, 5-vinylpiperidin-3-one, allylglycidyl ether,butadiene monoxide, butyl vinyl ether, dihydropyran-3-one, divinyl butylcarbonate, divinyl carbonate, divinyl crotonate, divinyl ether, divinylethylene carbonate, divinyl ethylene silicate, divinyl ethylene sulfate,divinyl ethylene sulfite, divinyl methoxypyrazine, divinylmethylphosphate, divinyl propylene carbonate, ethyl phosphate,methoxy-o-terphenyl, methyl phosphate, oxetan-2-yl-vinylamine,oxiranylvinylamine, vinyl carbonate, vinyl crotonate, vinylcyclopentanone, vinyl ethyl-2-furoate, vinyl ethylene carbonate, vinylethylene silicate, vinyl ethylene sulfate, vinyl ethylene sulfite, vinylmethacrylate, vinyl phosphate, vinyl-2-furoate, vinylcylopropanone,vinylethylene oxide, β-vinyl-γ-butyrolactone, or a mixture of any two ormore thereof. In some embodiments the electrode stabilizing additive maybe a cyclotriphosphazene that is substituted with F, alkyloxy,alkenyloxy, aryloxy, methoxy, allyloxy groups, or combinations thereof.For example, the additive may be a(divinyl)-(methoxy)(trifluoro)cyclotriphosphazene,(trivinyl)(difluoro)(methoxy)cyclotriphosphazene,(vinyl)(methoxy)(tetrafluoro)cyclotriphosphazene,(aryloxy)(tetrafluoro)(methoxy)-cyclotriphosphazene,(diaryloxy)(trifluoro)(methoxy)cyclotriphosphazene compounds, or amixture of two or more such compounds. In some embodiments, theelectrode stabilizing additive is vinyl ethylene carbonate, vinylcarbonate, or 1,2-diphenyl ether, or a mixture of any two or more suchcompounds.

Other representative electrode stabilizing additives may includecompounds with phenyl, naphthyl, anthracenyl, pyrrolyl, oxazolyl,furanyl, indolyl, carbazolyl, imidazolyl, or thiophenyl groups. Forexample, electrode stabilizing additives may be aryloxpyrrole, aryloxyethylene sulfate, aryloxy pyrazine, aryloxy-carbazole trivinylphosphate,aryloxy-ethyl-2-furoate, aryloxy-o-terphenyl, aryloxy-pyridazine,butyl-aryloxy-ether, divinyl diphenyl ether,(tetrahydro-furan-2-yl)-vinylamine, divinyl methoxybipyridine,methoxy-4-vinylbiphenyl, vinyl methoxy carbazole, vinyl methoxypiperidine, vinyl methoxypyrazine, vinyl methyl carbonate-allylanisole,vinyl pyridazine, 1-divinylimidazole, 3-vinyltetrahydrofuran, divinylfuran, divinyl methoxy furan, divinylpyrazine, vinyl methoxy imidazole,vinylmethoxy pyrrole, vinyl-tetrahydrofuran, 2,4-divinyl isooxazole, 3,4divinyl-1-methyl pyrrole, aryloxyoxetane, aryloxy-phenyl carbonate,aryloxy-piperidine, aryloxy-tetrahydrofuran, 2-aryl-cyclopropanone,2-diaryloxy-furoate, 4-allylanisole, aryloxy-carbazole,aryloxy-2-furoate, aryloxy-crotonate, aryloxy-cyclobutane,aryloxy-cyclopentanone, aryloxy-cyclopropanone,aryloxy-cycolophosphazene, aryloxy-ethylene silicate, aryloxy-ethylenesulfate, aryloxy-ethylene sulfite, aryloxy-imidazole,aryloxy-methacrylate, aryloxy-phosphate, aryloxy-pyrrole,aryloxy-quinoline, diaryloxy-cyclotriphosphazene, diaryloxy ethylenecarbonate, diaryloxy furan, diaryloxy methyl phosphate, diaryloxy-butylcarbonate, diaryloxy-crotonate, diaryloxy-diphenyl ether,diaryloxy-ethyl silicate, diaryloxy-ethylene silicate,diaryloxy-ethylene sulfate, diaryloxyethylene sulfite, diaryloxy-phenylcarbonate, diaryloxy-propylene carbonate, diphenyl carbonate, diphenyldiaryloxy silicate, diphenyl divinyl silicate, diphenyl ether, diphenylsilicate, divinyl methoxydiphenyl ether, divinyl phenyl carbonate,methoxycarbazole, or 2,4-dimethyl-6-hydroxy-pyrimidine, vinylmethoxyquinoline, pyridazine, vinyl pyridazine, quinoline, vinylquinoline, pyridine, vinyl pyridine, indole, vinyl indole,triethanolamine, 1,3-dimethyl butadiene, butadiene, vinyl ethylenecarbonate, vinyl carbonate, imidazole, vinyl imidazole, piperidine,vinyl piperidine, pyrimidine, vinyl pyrimidine, pyrazine, vinylpyrazine, isoquinoline, vinyl isoquinoline, quinoxaline, vinylquinoxaline, biphenyl, 1,2-diphenyl ether, 1,2-diphenylethane, oterphenyl, N-methyl pyrrole, naphthalene, or a mixture of any two ormore such compounds.

In other embodiments, electrode stabilizing additives includesubstituted or unsubstituted spirocyclic hydrocarbons containing atleast one oxygen atom and at least one alkenyl or alkynyl group. Forexample, such stabilizing additives include those having Formula X:

wherein A¹, A², A³, and A⁴ are independently O or CR¹²R¹³; provided thatA¹ is not O when G¹ is O, A² is not O when G² is O, A³ is not O when G³is O, and A⁴ is not O when G⁴ is O; G¹, G², G³, and G⁴ are independentlyO or CR¹²R¹³; provided that G¹ is not O when A¹ is O, G² is not O whenA² is O, G³ is not O when A³ is O, and G⁴ is not O when A⁴ is O; R¹⁰ andR¹¹ are independently a substituted or unsubstituted divalent alkenyl oralkynyl group; and R¹² and R¹³ at each occurrence are independently H,F, Cl, or a substituted or an unsubstituted alkyl, alkenyl, or alkynylgroup.

Representative examples of Formula X include, but are not limited to,3,9 divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane,3,9-divinyl-2,4,8-trioxaspiro[5.5]undecane,3,9-divinyl-2,4-dioxaspiro[5.5]undecane,3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, 3,9diethylidene-2,4,8-trioxaspiro[5.5]undecane,3,9-diethylidene-2,4-dioxaspiro[5.5]undecane,3,9-dimethylene-2,4,8,10-tetraoxaspiro[5.5]undecane,3,9-divinyl-1,5,7,11-tetraoxaspiro[5.5]undecane, 3,9dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane, 3,9diethylidene-1,5,7,11-tetraoxaspiro[5.5]undecane, or a mixture of anytwo or more such compounds. Furthermore, mixtures of any two or moreelectrode stabilizing additives may also be used in the electrolytes ofthe present invention.

In some embodiments, the electrode stabilizing additive is an anionreceptor. In some embodiments, the anion receptor is a Lewis acid. Inother embodiments, the anion receptor is a borane, a boronate, a borate,a borole, or a mixture of any two or more such compounds.

In some embodiments, the anion receptor is a compound of the Formula XI:

where, each R¹⁴, R¹⁵, and R¹⁶ are independently halogen, alkyl, aryl,halogen-substituted alkyl, halogen-substituted aryl, or OR¹⁷; or any twoof R¹⁴, R¹⁵, R¹⁶ and R¹⁷, together with the atoms to which they areattached, form a heterocyclic ring having 5-9 members, and R¹⁷ is ateach occurrence independently alkyl, aryl, halogen-substituted alkyl, orhalogen-substituted aryl. In some such embodiments, R¹⁴, R¹⁵, and R¹⁶are independently halogen, alkyl, aryl, halogen-substituted alkyl, orhalogen-substituted aryl; or any two of R¹⁴, R¹⁵, and R¹⁶, together withthe boron to which they are attached, form a heterocyclic ring having5-9 members.

In some embodiments, the anion receptors include, but not limited to,tri(propyl)borate, tris(1,1,1,3,3,3-hexafluoro-propan-2-yl)borate,tris(1,1,1,3,3,3-hexafluoro-2-phenyl-propan-2-yl)borate,tris(1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-yl)borate,triphenyl borate, tris(4-fluorophenyl)borate,tris(2,4-difluorophenyl)borate, tris(2,3,5,6-tetrafluorophenyl)borate,tris(pentafluorophenyl)borate, tris(3-(trifluoromethyl)phenyl)borate,tris(3,5-bis(trifluoromethyl)phenyl)borate,tris(pentafluorophenyl)borane, or a mixture of any two or more thereof.Further suitable additives include2-(2,4-difluorophenyl)-4-fluoro-1,3,2-benzodioxaborole,2-(3-trifluoromethyl phenyl)-4-fluoro-1,3,2-benzodioxaborole,2,5-bis(trifluoromethyl)phenyl-4-fluoro-1,3,2-benzodioxaborole,2-(4-fluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole,2-(2,4-difluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole,2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole,2-(2-trifluoromethyl phenyl)-tetrafluoro-1,3,2-benzodioxaborole,2,5-bis(trifluoromethyl phenyl)-tetrafluoro-1,3,2-benzodioxaborole,2-phenyl-4,4,5,5-tetra(trifluoromethyl)-1,3,2-benzodioxaborolane,2-(3,5-difluorophenyl-4,4,5,5-tetrakis(trifluoromethyl)-1,3,2-dioxaborolane,2-(3,5-difluorophenyl-4,4,5,5-tetrakis(trifluoromethyl)-1,3,2-dioxaborolane,2-pentafluorophenyl-4,4,5,5-tetrakis(trifluoromethyl)-1,3,2-dioxaborolane,bis(1,1,1,3,3,3-hexafluoroisopropyl)phenyl-boronate,bis(1,1,1,3,3,3-hexafluoroisopropyl)-3,5-difluorophenylboronate,bis(1,1,1,3,3,3-hexafluoroisopropyl) pentafluorophenylboronate, or amixture of any two or more such compounds.

In some embodiments, each anion receptor is present at a concentrationof about 0.001 to about 10 wt %.

Lithium (chelato)borates such as Li[B(C₂O₄)₂] and Li(C₂O₄)BF₂, orlithium (chelato)phosphates such as LiPF₂(C₂O₄) may also be used as thealkali metal salt, or as an electrode stabilizing additive, in someembodiments. As such, the alkali metal salt may be other thanLi[B(C₂O₄)₂], Li[BF₂(C₂O₄)], Li[PF₄(C₂O₄)] or Li[PF₂(C₂O₄)₂]; and theelectrolyte may include, as a electrode stabilizing additive,Li[B(C₂O₄)₂], Li[BF₂(C₂O₄)], Li[PF₄(C₂O₄)], Li[PF₂(C₂O₄)₂], or a mixtureof two or more such materials. Such electrode stabilizing materials maybe present from about 0.001 to about 8 wt %. In some other embodiments,the lithium salt is other than Li₂B₁₂X_(12−n)H_(n), orLi₂B₁₀X_(10−n′)H_(n′); and the electrolyte includes as a electrolyteadditive, Li₂B₁₂X_(12−n)H_(n), Li₂B₁₀X_(10−n′)H_(n′), or a mixture oftwo or more of such compounds. Such electrolyte additives may be presentfrom about 0.001 to 15 wt %. In such compounds, X is OH, OCH₃, F, Cl,Br, or I, n is an integer from 0 to 12, and n′ is an integer from 0 to10.

In some embodiments, the electrode stabilizing additive is any of theabove electrode stabilizing additives, or a mixture of any two or moresuch additives.

Suitable polar aprotic solvents for use in the non-aqueous electrolytesinclude but not limited to, for example, siloxane, polysiloxane, ethylacetate, propyl acetate, ethylene carbonate, propylene carbonate,dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethylether, diethyl ether, methyl acetate, gamma-butyrolactone, sulfolane, ora mixture of any two or more thereof. Protic solvents such as water andalcohols cannot be used with the present invention.

In some embodiments, the inventive electrolyte is a gel electrolytecomprising: at least one aprotic solvent; at least one lithium salt; atleast one crosslinking agent; at least one monofunctional monomericcompound; and at least one radical reaction initiator. In someembodiments, the gel electrolyte can also comprise other electrodestabilization additives and other electrolyte additives.

In some embodiments, suitable crosslinking agents may be represented byFormula XII:

where R¹⁸, R¹⁹, R²⁰, and R²¹ are each independently hydrogen, asubstituted or unsubstituted alkyl group having from 1 to 12 carbonatoms, or a substituted or unsubstituted alkenyl group having from 2 to12 carbon atoms; and where X′ is a hydrogen, methyl, or ethyl group, andn′″ is an integer from 1 to 15.

Monofunctional monomeric compounds may be used for the control of thecrosslinking density of the gel electrolyte. Suitable monofunctionalmonomeric compounds include those of Formula XIII:

where R²² is an alkyl group having from 1 to 12 carbon atoms; R²³ andR²⁴ are each independently a hydrogen, a substituted or unsubstitutedalkyl group having from 1 to 12 carbon atoms, or a substituted orunsubstituted alkenyl group having from 2 to 12 carbon atoms; X′ ishydrogen, methyl or ethyl group; and q″ is an integer from 1 to 20.

Crosslinking agents and monofunctional monomeric compounds provide aphysical framework, or gel, after crosslinking to host the liquid phase.Variation of the amount of the crosslinking agent and monofunctionalmonomeric compound in the gel may impact the conductivity of the gelelectrolyte, due to changes in viscosity. Lower viscosity gels areprepared with higher concentrations of monofunctional monomericcompound, as compared to the concentration of monofunctional monomericcompound used for higher viscosity gels. Without being bound by theory,higher viscosity gels may be expected to have lower electrochemicalconductivity, while lower viscosity gels may be expected to have higherelectrochemical conductivity. However, other electrochemical propertiesof the gel electrolyte, or an electrochemical cell prepared with the gelelectrolyte, such as oxidation potential and reduction potential, arenot expected to be impacted.

Polymerization of crosslinking agents and monofunctional monomericcompounds are known to those of skill in the art. For example,monofunctional monomeric compounds may be polymerized by thermal andphoto initiation. Representative thermal initiators include, but are notlimited to, an azo compound, a peroxide compound, bismaleimide, or amixture of any two or more thereof. One example of an azo compound isazoisobutyronitrile. One example of a peroxide compound isbenzoylperoxide. Representative photo initiators include, but are notlimited to, 1-hydroxyl-phenyl-ketone, benzophenone,2-hydroxyl-2-methyl-1-phenyl-propanone,2-hydroxyl-1-[4-(2-hydroxyl)phenyl]-2-methyl-1-propanone,methylbenzoylformate, oxy-phenyl-acetic acid2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic2-[2-hydroxy-ethoxy]-ethyl ester, α,α-dimethoxy-α-phenylacetophenone,2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-propanone,diphenyl (2,4,6-trimethylthio)phenyl)-phosphine oxide, phosphine oxide,phenyl bis(2,4,6-trimethyl benzoyl), bis(η⁵-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium, iodonium(4-methylphenyl)-[4-(2-methylpropyl)phenyl]-hexafluorophosphate, or amixture of two or more thereof. In some instances the photoinitiator isa UV initiator.

Non-aqueous electrolytes may further include redox shuttles to provideovercharge protection of the lithium battery. See US Patent ApplicationNos. 2007/0178370; 2007/0072085; 2006/0199080; 2005/0227143;2005/0221196; 2005/0221168. Redox shuttle additives, capable of beingoxidized or reduced in the non-aqueous electrolyte. In some embodiments,the redox shuttle additive is a substituted or unsubstituted ferrocenecompound, such as those described in U.S. Pat. No. 4,857,423, or asubstituted aromatic compound. The substituted aromatic compoundssuitable for use in the present invention may generally be of formulaXIV:

where each of R²⁵, R²⁶, R²⁷, R²⁸, R²⁹ and R³⁰ of Formula XIV areindependently selected from H, —F, —Cl, —Br, —I, haloalkyl, cycloalkyl,alkyl, alkenyl, aryl, heteroaryl, —CN, or —NO₂, —O-alkyl, —O-aryl,—O-heteroaryl, —O-alkenyl, —O-alkynyl, —S-alkyl, —S-aryl, —S-alkenyl,—S-alkynyl, —S-heteroaryl, and the groups:

or any two adjacent groups of R²⁵, R²⁶, R²⁷, R²⁸, R²⁹ and R³⁰ togethermay form a fused ary or heteroaryl ring; and where each R³¹, R³² and R³³may independently be a hydrogen, halogen, an alkyl group, an aryl group,a halogen substituted alkyl group, or a halogen substituted aryl group;and where each R³⁴, R³⁵ and R³⁶ may independently be a halogen atom, analkyl group, an aryl group, a halogen substituted alkyl group, or ahalogen substituted aryl group; where M⁺ is a cation, A⁻ is an anion,and where at least one of R²⁵, R²⁶, R²⁷, R²⁸, R²⁹ and R³⁰ is not H.Also, two or more of R²⁵, R²⁹ and R³⁰ may each independently be an—O-alkyl, —O-alkenyl, —O-alkynyl, —O-aryl, or —O-heteroaryl group. Insome embodiments, R²⁵ is H. In other embodiments, the redox shuttleadditive may be 2,5-di-(tert-butyl)-1,4-dimethoxybenzene,(tetrafluorobenzo-1,2-dioxyl)-pentafluorophenyl-borane, or a mixture ofany two or more such compounds. In another embodiment, the redox shuttleadditive is a borate or heteroborate cluster ion, e.g., Li₂B₁₀X₁₀ orLi₂B₁₂X₁₂ where each X is independently H, F, Cl, Br, I, OCH₃, or OH.Suitable borate and heteroborate salts include Li₂B₁₀Cl₁₀,Li₂B₁₀OH_(q)Cl_(q′), Li₂B₁₀H₂Cl₈, Li₂B₁₀Cl₈(OH)₂, Li₂B₁₀Br₁₀,Li₂B₁₂Cl₁₂, and those described in U.S. Patent Publication No.2005/0227143, where q is an integer from 3 to 5 and q′ is an integerfrom 5 to 9 and the sum of q and q′ is 10. The redox shuttle additivesmay be a mixture of any two or more of the materials identified above asredox shuttle additives.

Definitions

The following terms are used throughout as defined below.

For the purposes of this disclosure and unless otherwise specified, “a”or “an” means “one or more.”

The inventions illustratively described herein may suitably be practicedin the absence of any element or elements, limitation or limitations,not specifically disclosed herein. Thus, for example, the terms“comprising,” “including,” “containing,” etc. shall be read expansivelyand without limitation. Additionally, the terms and expressions employedherein have been used as terms of description and not of limitation, andthere is no intention in the use of such terms and expressions ofexcluding any equivalents of the features shown and described orportions thereof, but it is recognized that various modifications arepossible within the scope of the invention claimed. Additionally thephrase “consisting essentially of” will be understood to include thoseelements specifically recited and those additional elements that do notmaterially affect the basic and novel characteristics of the claimedinvention. The phrase “consisting of” excludes any element notspecifically specified.

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent depending upon the context inwhich it is used. If there are uses of the term which are not clear topersons of ordinary skill in the art, given the context in which it isused, “about” will mean up to plus or minus 10% of the particular term.

In general, “substituted” refers to an organic group as defined below(e.g., an alkyl group) in which one or more bonds to a hydrogen atomcontained therein are replaced by a bond to non-hydrogen or non-carbonatoms. Substituted groups also include groups in which one or more bondsto a carbon(s) or hydrogen(s) atom are replaced by one or more bonds,including double or triple bonds, to a heteroatom. Thus, a substitutedgroup will be substituted with one or more substituents, unlessotherwise specified. In some embodiments, a substituted group issubstituted with 1, 2, 3, 4, 5, or 6 substituents. Examples ofsubstituent groups include: halogens (i.e., F, Cl, Br, and I);hydroxyls; alkoxy, alkenoxy, alkynoxy, aryloxy, aralkyloxy,heterocyclyloxy, and heterocyclylalkoxy groups; carbonyls (oxo);carboxyls; esters; ethers; urethanes; oximes; hydroxylamines;alkoxyamines; aralkoxyamines; thiols; sulfides; sulfoxides; sulfones;sulfonyls; sulfonamides; amines; N-oxides; hydrazines; hydrazides;hydrazones; azides; amides; ureas; amidines; guanidines; enamines;imides; isocyanates; isothiocyanates; cyanates; thiocyanates; imines;nitro groups; nitriles (i.e., CN); and the like.

Alkyl groups include straight chain and branched alkyl groups havingfrom 1 to about 20 carbon atoms, and typically from 1 to 12 carbons or,in some embodiments, from 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Alkylgroups further include cycloalkyl groups as defined below. Examples ofstraight chain alkyl groups include those with from 1 to 8 carbon atomssuch as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl,and n-octyl groups. Examples of branched alkyl groups include, but arenot limited to, isopropyl, iso-butyl, sec-butyl, tert-butyl, neopentyl,isopentyl, and 2,2-dimethylpropyl groups. Representative substitutedalkyl groups can be substituted one or more times with substituents suchas those listed above.

Cycloalkyl groups are cyclic alkyl groups such as, but not limited to,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, andcyclooctyl groups. In some embodiments, the cycloalkyl group has 3 to 8ring members, whereas in other embodiments the number of ring carbonatoms range from 3 to 5, 3 to 6, or 3 to 7. Cycloalkyl groups furtherinclude mono-, bicyclic and polycyclic ring systems, such as, forexample bridged cycloalkyl groups as described below, and fused rings,such as, but not limited to, decalinyl, and the like. In someembodiments, polycyclic cycloalkyl groups have three rings. Substitutedcycloalkyl groups can be substituted one or more times with,non-hydrogen and non-carbon groups as defined above. However,substituted cycloalkyl groups also include rings that are substitutedwith straight or branched chain alkyl groups as defined above.Representative substituted cycloalkyl groups can be mono-substituted orsubstituted more than once, such as, but not limited to, 2,2-, 2,3-,2,4-2,5- or 2,6-disubstituted cyclohexyl groups, which can besubstituted with substituents such as those listed above. Cycloalkylgroups can also be bridged cycloalkyl groups in which two or morehydrogen atoms are replaced by an alkylene bridge, wherein the bridgecan contain 2 to 6 carbon atoms if two hydrogen atoms are located on thesame carbon atom, or 1 to 5 carbon atoms, if the two hydrogen atoms arelocated on adjacent carbon atoms, or 2 to 4 carbon atoms if the twohydrogen atoms are located on carbon atoms separated by 1 or 2 carbonatoms. Bridged cycloalkyl groups can be bicyclic, such as, for examplebicyclo[2.1.1]hexane, or tricyclic, such as, for example, adamantyl.Representative bridged cycloalkyl groups include bicyclo[2.1.1]hexyl,bicyclo[2.2.1]heptyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl,bicyclo[3.2.2]nonyl, bicyclo[3.3.1]nonyl, bicyclo[3.3.2]decanyl,adamantyl, noradamantyl, bornyl, or norbornyl groups. Substitutedbridged cycloalkyl groups can be substituted one or more times withnon-hydrogen and non-carbon groups as defined above. Representativesubstituted bridged cycloalkyl groups can be mono-substituted orsubstituted more than once, such as, but not limited to, mono-, di- ortri-substituted adamantyl groups, which can be substituted withsubstituents such as those listed above.

Cycloalkylalkyl groups are alkyl groups as defined above in which ahydrogen or carbon bond of an alkyl group is replaced with a bond to acycloalkyl group as defined above. In some embodiments, cycloalkylalkylgroups have from 4 to 20 carbon atoms, 4 to 16 carbon atoms, andtypically 4 to 10 carbon atoms. Substituted cycloalkylalkyl groups canbe substituted at the alkyl, the cycloalkyl or both the alkyl andcycloalkyl portions of the group. Representative substitutedcycloalkylalkyl groups can be mono-substituted or substituted more thanonce, such as, but not limited to, mono-, di- or tri-substituted withsubstituents such as those listed above.

Alkenyl groups include straight and branched chain and cycloalkyl groupsas defined above, except that at least one double bond exists betweentwo carbon atoms. Thus, alkenyl groups have from 2 to about 20 carbonatoms, and typically from 2 to 12 carbons or, in some embodiments, from2 to 8, 2 to 6, or 2 to 4 carbon atoms. In some embodiments, alkenylgroups include cycloalkenyl groups having from 4 to 20 carbon atoms, 5to 20 carbon atoms, 5 to 10 carbon atoms, or even 5, 6, 7, or 8 carbonatoms. Examples include, but are not limited to vinyl, allyl,—CH═CH(CH₃), —CH═C(CH₃)₂, —C(CH₃)═CH₂, —C(CH₃)═CH(CH₃), CH═CHCH═CH₂,C(CH₂CH₃)═CH₂, cyclohexenyl, cyclopentenyl, cyclohexadienyl, butadienyl,pentadienyl, and hexadienyl, among others. Representative substitutedalkenyl groups can be mono-substituted or substituted more than once,such as, but not limited to, mono-, di- or tri-substituted withsubstituents such as those listed above.

Cycloalkenylalkyl groups are alkyl groups as defined above in which ahydrogen or carbon bond of the alkyl group is replaced with a bond to acycloalkenyl group as defined above. Substituted cycloalkylalkenylgroups can be substituted at the alkyl, the cycloalkenyl or both thealkyl and cycloalkenyl portions of the group. Representative substitutedcycloalkenylalkyl groups can be substituted one or more times withsubstituents such as those listed above.

Alkynyl groups include straight and branched chain alkyl groups, exceptthat at least one triple bond exists between two carbon atoms. Thus,alkynyl groups have from 2 to about 20 carbon atoms, and typically from2 to 12 carbons or, in some embodiments, from 2 to 8, 2 to 6, or 2 to 4carbon atoms. Examples include, but are not limited to —C≡CH, —C≡C(CH₃),—C≡C(CH₂CH₃), —CH₂C≡CH, —CH₂CC(CH₃), and —CH₂CC(CH₂CH₃), among others.Representative substituted alkynyl groups can be mono-substituted orsubstituted more than once, such as, but not limited to, mono-, di- ortri-substituted with substituents such as those listed above.

Aryl groups are cyclic aromatic hydrocarbons that do not containheteroatoms. Aryl groups include monocyclic, bicyclic and polycyclicring systems. Thus, aryl groups include, but are not limited to,cyclopentadienyl, phenyl, azulenyl, heptalenyl, biphenylenyl, indacenyl,fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl,chrysenyl, biphenyl, anthracenyl, indenyl, indanyl, pentalenyl, andnaphthyl groups. In some embodiments, aryl groups contain 5-14 carbons,and in others from 5 to 12 or even 6-10 carbon atoms in the ringportions of the groups. Although the phrase “aryl groups” includesgroups containing fused rings, such as fused aromatic-aliphatic ringsystems (e.g., indanyl, tetrahydronaphthyl, and the like), it does notinclude aryl groups that have other groups, such as alkyl or halogroups, bonded to one of the ring members. Rather, groups such as tolylare referred to as substituted aryl groups. Representative substitutedaryl groups can be mono-substituted or substituted more than once. Forexample, monosubstituted aryl groups include, but are not limited to,2-, 3-, 4-, 5-, or 6-substituted phenyl or naphthyl groups, which can besubstituted with substituents such as those listed above.

Aralkyl groups are alkyl groups as defined above in which a hydrogen orcarbon bond of an alkyl group is replaced with a bond to an aryl groupas defined above. In some embodiments, aralkyl groups contain 7 to 20carbon atoms, 7 to 14 carbon atoms or 7 to 10 carbon atoms. Substitutedaralkyl groups can be substituted at the alkyl, the aryl or both thealkyl and aryl portions of the group. Representative aralkyl groupsinclude but are not limited to benzyl and phenethyl groups and fused(cycloalkylaryl)alkyl groups such as 4-ethyl-indanyl. Representativesubstituted aralkyl groups can be substituted one or more times withsubstituents such as those listed above.

Heterocyclyl groups include aromatic (also referred to as heteroaryl)and non-aromatic ring compounds containing 3 or more ring members, ofwhich one or more is a heteroatom such as, but not limited to, N, O, andS. In some embodiments, heterocyclyl groups include 3 to 20 ringmembers, whereas other such groups have 3 to 6, 3 to 10, 3 to 12, or 3to 15 ring members. Heterocyclyl groups encompass unsaturated, partiallysaturated and saturated ring systems, such as, for example, imidazolyl,imidazolinyl and imidazolidinyl groups. The phrase “heterocyclyl group”includes fused ring species including those comprising fused aromaticand non-aromatic groups, such as, for example, benzotriazolyl,2,3-dihydrobenzo[1,4]dioxinyl, and benzo[1,3]dioxolyl. The phrase alsoincludes bridged polycyclic ring systems containing a heteroatom suchas, but not limited to, quinuclidyl. However, the phrase does notinclude heterocyclyl groups that have other groups, such as alkyl, oxoor halo groups, bonded to one of the ring members. Rather, these arereferred to as “substituted heterocyclyl groups”. Heterocyclyl groupsinclude, but are not limited to, aziridinyl, azetidinyl, pyrrolidinyl,imidazolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydrothiophenyl,tetrahydrofuranyl, dioxolyl, furanyl, thiophenyl, pyrrolyl, pyrrolinyl,imidazolyl, imidazolinyl, pyrazolyl, pyrazolinyl, triazolyl, tetrazolyl,oxazolyl, isoxazolyl, thiazolyl, thiazolinyl, isothiazolyl,thiadiazolyl, oxadiazolyl, piperidyl, piperazinyl, morpholinyl,thiomorpholinyl, tetrahydropyranyl, tetrahydrothiopyranyl, oxathiane,dioxyl, dithianyl, pyranyl, pyridyl, pyrimidinyl, pyridazinyl,pyrazinyl, triazinyl, dihydropyridyl, dihydrodithiinyl,dihydrodithionyl, homopiperazinyl, quinuclidyl, indolyl, indolinyl,isoindolyl, azaindolyl (pyrrolopyridyl), indazolyl, indolizinyl,benzotriazolyl, benzimidazolyl, benzofuranyl, benzothiophenyl,benzthiazolyl, benzoxadiazolyl, benzoxazinyl, benzodithiinyl,benzoxathiinyl, benzothiazinyl, benzoxazolyl, benzothiazolyl,benzothiadiazolyl, benzo[1,3]dioxolyl, pyrazolopyridyl, imidazopyridyl(azabenzimidazolyl), triazolopyridyl, isoxazolopyridyl, purinyl,xanthinyl, adeninyl, guaninyl, quinolinyl, isoquinolinyl, quinolizinyl,quinoxalinyl, quinazolinyl, cinnolinyl, phthalazinyl, naphthyridinyl,pteridinyl, thianaphthalenyl, dihydrobenzothiazinyl,dihydrobenzofuranyl, dihydroindolyl, dihydrobenzodioxinyl,tetrahydroindolyl, tetrahydroindazolyl, tetrahydrobenzimidazolyl,tetrahydrobenzotriazolyl, tetrahydropyrrolopyridyl,tetrahydropyrazolopyridyl, tetrahydroimidazopyridyl,tetrahydrotriazolopyridyl, and tetrahydroquinolinyl groups.Representative substituted heterocyclyl groups can be mono-substitutedor substituted more than once, such as, but not limited to, pyridyl ormorpholinyl groups, which are 2-, 3-, 4-, 5-, or 6-substituted, ordisubstituted with various substituents such as those listed above.

Heteroaryl groups are aromatic ring compounds containing 5 or more ringmembers, of which, one or more is a heteroatom such as, but not limitedto, N, O, and S. Heteroaryl groups include, but are not limited to,groups such as pyrrolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl,isoxazolyl, thiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl,thiophenyl, benzothiophenyl, furanyl, benzofuranyl, indolyl, azaindolyl(pyrrolopyridyl), indazolyl, benzimidazolyl, imidazopyridyl(azabenzimidazolyl), pyrazolopyridyl, triazolopyridyl, benzotriazolyl,benzoxazolyl, benzothiazolyl, benzothiadiazolyl, imidazopyridyl,isoxazolopyridyl, thianaphthalenyl, purinyl, xanthinyl, adeninyl,guaninyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, quinoxalinyl,and quinazolinyl groups. Although the phrase “heteroaryl groups”includes fused ring compounds such as indolyl and 2,3-dihydro indolyl,the phrase does not include heteroaryl groups that have other groupsbonded to one of the ring members, such as alkyl groups. Rather,heteroaryl groups with such substitution are referred to as “substitutedheteroaryl groups.” Representative substituted heteroaryl groups can besubstituted one or more times with various substituents such as thoselisted above.

Heterocyclylalkyl groups are alkyl groups as defined above in which ahydrogen or carbon bond of an alkyl group is replaced with a bond to aheterocyclyl group as defined above. Substituted heterocyclylalkylgroups can be substituted at the alkyl, the heterocyclyl or both thealkyl and heterocyclyl portions of the group. Representativeheterocyclyl alkyl groups include, but are not limited to,4-ethyl-morpholinyl, 4-propylmorpholinyl, furan-2-yl methyl, furan-3-ylmethyl, pyridine-3-yl methyl, tetrahydrofuran-2-yl ethyl, and indol-2-ylpropyl. Representative substituted heterocyclylalkyl groups can besubstituted one or more times with substituents such as those listedabove.

Heteroaralkyl groups are alkyl groups as defined above in which ahydrogen or carbon bond of an alkyl group is replaced with a bond to aheteroaryl group as defined above. Substituted heteroaralkyl groups canbe substituted at the alkyl, the heteroaryl or both the alkyl andheteroaryl portions of the group. Representative substitutedheteroaralkyl groups can be substituted one or more times withsubstituents such as those listed above.

Alkoxy groups are hydroxyl groups (—OH) in which the bond to thehydrogen atom is replaced by a bond to a carbon atom of a substituted orunsubstituted alkyl group as defined above. Examples of linear alkoxygroups include but are not limited to methoxy, ethoxy, propoxy, butoxy,pentoxy, hexoxy, and the like. Examples of branched alkoxy groupsinclude but are not limited to isopropoxy, sec-butoxy, tert-butoxy,isopentoxy, isohexoxy, and the like. Examples of cycloalkoxy groupsinclude but are not limited to cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy, and the like. Representative substitutedalkoxy groups can be substituted one or more times with substituentssuch as those listed above.

The terms “aryloxy” and “arylalkoxy” refer to, respectively, asubstituted or unsubstituted aryl group bonded to an oxygen atom and asubstituted or unsubstituted aralkyl group bonded to the oxygen atom atthe alkyl. Examples include but are not limited to phenoxy, naphthyloxy,and benzyloxy. Representative substituted aryloxy and arylalkoxy groupscan be substituted one or more times with substituents such as thoselisted above.

The term “amide” (or “amido”) includes C- and N-amide groups, i.e.,—C(O)NR³⁷R³⁸, and —NR³⁷C(O)R³⁸ groups, respectively. The term “amine”(or “amino”) as used herein refers to —NHR³⁷ and —NR³⁷R³⁸ groups. R³⁷and R³⁸ are at each occurrence independently H, substituted orunsubstituted C₁₋₈ alkyl, substituted or unsubstituted C₁₋₈ alkenyl,substituted or unsubstituted C₁₋₈ alkynyl, substituted or unsubstitutedaryl, substituted or unsubstituted aralkyl, substituted or unsubstitutedheterocyclyl, substituted or unsubstituted heterocyclylalkyl,substituted or unsubstituted cycloalkyl, and substituted orunsubstituted cycloalkylalkyl as defined herein. In some embodiments,the amine is NH₂, methylamino, dimethylamino, ethylamino, diethylamino,propylamino, isopropylamino, phenylamino, or benzylamino.

One skilled in the art will readily realize that all ranges discussedcan and do necessarily also describe all subranges therein for allpurposes and that all such subranges also form part and parcel of thisinvention. Any listed range can be easily recognized as sufficientlydescribing and enabling the same range being broken down into at leastequal halves, thirds, quarters, fifths, tenths, etc. As a non-limitingexample, each range discussed herein can be readily broken down into alower third, middle third and upper third, etc.

All publications, patent applications, issued patents, and otherdocuments referred to in this specification are herein incorporated byreference as if each individual publication, patent application, issuedpatent, or other document was specifically and individually indicated tobe incorporated by reference in its entirety. Definitions that arecontained in text incorporated by reference are excluded to the extentthat they contradict definitions in this disclosure.

The present invention, thus generally described, will be understood morereadily by reference to the following examples, which are provided byway of illustration and are not intended to be limiting of the presentinvention.

EXAMPLES Example 1

After the formation cycle, a 200 mAh Li₄Ti₅O₁₂/Li_(1+x)Mn_(2−x)O₄lithium-ion cell exhibited slight swelling, indicating a small amount ofgas was generated during the formation cycle. By contrast, aLi₄Ti₅O₁₂/Li_(1+x)Mn_(2-x)O₄ lithium-ion cell including 1 wt %chloro[2-[2-(2-methoxyethoxyl)ethoxy]ethoxy]dimethylsilane failed toshow any observable amount of gas when tested under the same conditionsas the cell without the silane.

Example 2

FIG. 1 is a composite illustration of a composite photograph of cellsbefore (C) and after (A,B) charging. Each cell is aLi₄Ti₅O₁₂/Li_(1+x)Mn_(2−x)O₄ lithium-ion cell. Cell (A) was preparedwith 1 wt % chloro[2-[2-(2-methoxyethoxyl)ethoxy]ethoxy]dimethylsilaneas a surface modification agent, and cell (B) did not contain anysurface modification agent. Cell (C) did not undergo any charging. Cells(A) and (B) were aged at 100% state of charge at 55° C. for 26 daysprior to the photographs being taken. Plastic bags 110 were used toprevent shorting, and gas collecting pouches 120 were used to monitorthe amount of gas generated. As evidenced by the swelling of the pouch132, the cell without surface modification agent (A) generated much moregas than was generated in the cell with the surface modification agent(B) 131. The pouch of cell C did not exhibit any swelling 130.

What is claimed is:
 1. An active material for an electrochemical device:wherein: a surface of the active material is modified by a first surfacemodification agent selected from the group consisting of aluminumsec-butoxide, diethylaluminum ethoxide, tris(ethylmethylamido)aluminum,triethylaluminum, triisobutylaluminum, trimethylaluminum,tris(diethylamido)aluminum, tris(ethylmethylamido)aluminum,trimethylarsine, diborane, trimethylboron,bis(N,N′-diisopropylacetaminato)cobalt (II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper (II),bis(N,N′-di-tert-butylacetamidinato)iron (II), triethylgallium,triisopropylgallium, trimethylgallium, tri(dimethylamido)gallium,tri-tert-butylgallium, digermane, germane, tetramethylgermanium, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium acetylacetonate, triethylindium,tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, pentakis(dimethylamido)tantalum (V),tantalum (V) ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV)tert-butoxide, vanadium (V) oxytriisopropoxide,bis(tert-butylimido)bis(dimethylamido)tungsten (VI), tungstenhexacarbonyl, tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium(III) butoxide, diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) tert-butoxide,and a mixture of any two or more thereof.
 2. The active material ofclaim 1, wherein the surface active agent further comprises a secondsurface modification agent selected from the group consisting of:aluminum sec-butoxide, aluminum tribromide, aluminum trichloride,diethylaluminum ethoxide, tris(ethylmethylamido)aluminum,triethylaluminum, triisobutylaluminum, trimethylaluminum,tris(diethylamido)aluminum, tris(ethylmethylamido)aluminum,trimethylarsine, diborane, trimethylboron,bis(N,N′-diisopropylacetaminato)cobalt (II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper (II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III) butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide, and a mixture ofany two or more thereof.
 3. The active material of claim 1, wherein thesurface active agent further comprises a second surface modificationagent selected from the group consisting of ammonia, phosphine, ahalophosphine, a alkylphosphine, a haloalkylphosphine, an alkylamine,moisture, and a mixture of any two or more thereof.
 4. An electrodecomprising an active material for an electrochemical device, a currentcollector, and a binder; wherein: a surface of the active material ismodified by a first surface modification agent selected from the groupconsisting of aluminum sec-butoxide, diethylaluminum ethoxide,tris(ethylmethylamido)aluminum, triethylaluminum, triisobutylaluminum,trimethylaluminum, tris(diethylamido)aluminum,tris(ethylmethylamido)aluminum, trimethylarsine, diborane,trimethylboron, bis(N,N′-diisopropylacetaminato)cobalt (II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper (II),bis(N,N′-di-tert-butylacetamidinato)iron (II), triethylgallium,triisopropylgallium, trimethylgallium, tri(dimethylamido)gallium,tri-tert-butylgallium, digermane, germane, tetramethylgermanium, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium acetylacetonate, triethylindium,tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, pentakis(dimethylamido)tantalum (V),tantalum (V) ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV)tert-butoxide, vanadium (V) oxytriisopropoxide,bis(tert-butylimido)bis(dimethylamido)tungsten (VI), tungstenhexacarbonyl, tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium(III) butoxide, diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) tert-butoxide,and a mixture of any two or more thereof.
 5. The electrode of claim 4,wherein the surface active agent further comprises a second surfacemodification agent selected from the group consisting of: aluminumsec-butoxide, aluminum tribromide, aluminum trichloride, diethylaluminumethoxide, tris(ethylmethylamido)aluminum, triethylaluminum,triisobutylaluminum, trimethylaluminum, tris(diethylamido)aluminum,tris(ethylmethylamido)aluminum, trimethylarsine, diborane,trimethylboron, bis(N,N′-diisopropylacetaminato)cobalt (II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper (II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III) butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide, and a mixture ofany two or more thereof.
 6. The electrode of claim 4, wherein thesurface active agent further comprises a second surface modificationagent selected from the group consisting of ammonia, phosphine, ahalophosphine, a alkylphosphine, a haloalkylphosphine, an alkylamine,moisture, and a mixture of any two or more thereof.
 7. The electrode ofclaim 4, wherein the binder is polyvinylidene difluoride, copolymer ofpolyvinylidene difluoride and hexafluoropropylene, or a mixture thereof.8. The electrode of claim 4 further comprising a conductive fillingselected from the group consisting of carbon black, carbon fiber,graphite, a metallic nano powder, and a mixture of any two or morethereof.
 9. The electrode of claim 4 which is a negative electrode. 10.The electrode of claim 4 which is a positive electrode.
 11. An activematerial for an electrochemical device: wherein: a surface of the activematerial is modified by a first surface modification agent and a secondsurface modification agent; the first surface modification agent is acompound of Formula VIII, Formula IX, or a mixture thereof, Formula VIIIis M-(R⁸)_(p); Formula IX is M-(O—R⁹)_(p); M is a metal; R⁸ and R⁹ areeach independently hydrogen, alkoxy, alkyl, aryl, or aminoalkyl; and pis an integer from 1 to 6; and the second surface modification agentselected from the group consisting of: aluminum sec-butoxide, aluminumtribromide, aluminum trichloride, diethylaluminum ethoxide,tris(ethylmethylamido)aluminum, triethylaluminum, triisobutylaluminum,trimethylaluminum, tris(diethylamido)aluminum,tris(ethylmethylamido)aluminum, trimethylarsine, diborane,trimethylboron, bis(N,N′-diisopropylacetaminato)cobalt (II),dicarbonyl(cyclopentadienyl)cobalt (I),(N,N′-diisopropylacetaminato)copper (II),bis(N,N′-di-tert-butylacetamidinato)iron (II), gallium tribromide,gallium trichloride, triethylgallium, triisopropylgallium,trimethylgallium, tri(dimethylamido)gallium, tri-tert-butylgallium,digermane, germane, tetramethylgermanium, hafnium (IV) chloride, hafnium(IV) tert-butoxide, tetrakis(diethylamido)hafnium (IV),tetrakis(dimethylamido)hafnium (IV), tetrakis(ethylmethylamido)hafnium(IV), indium trichloride, indium(I) iodide, indium acetylacetonate,triethylindium, tris(N,N′-Di-tert-butylacetamidinato)lanthanum (III),bis(pentaethylcyclopentadienyl)magnesium, molybdenum hexacarbonyl,molybdenum (V) chloride, molybdenum (VI) fluoride,N,N-dimethylhydrazine, ammonia, azidotrimethylsilane, niobium (V)chloride, niobium (V) ethoxide, bis(methylcyclopentadienyl)nickel (II),phosphine, tert-butylphosphine, tris(trimethylsilyl)phosphine,cyclopentadienyl(trimethyl)platinum (IV),bis(ethylcyclopentadienyl)ruthenium (II), trimethylantimony,tris(dimethylamido)antimony, 2,4,6,8-tetramethylcyclotetrasiloxane,dimethoxydimethylsilane, disilane, methylsilane,octamethylcyclotetrasiloxane, silane, tris(isopropoxy)silanol,tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol,pentakis(dimethylamido)tantalum (V), tantalum (V) chloride, tantalum (V)ethoxide, tris(diethylamino)(tert-butylimido)tantalum (V),bis(diethylamido)bis(dimethylamido)titanium (IV),tetrakis(diethylamido)titanium (IV), tetrakis(dimethylamido)titanium(IV), tetrakis(ethylmethylamido)titanium (IV), titanium (IV) bromide,titanium (IV) chloride, titanium (IV) tert-butoxide, vanadium (V)oxytriisopropoxide, bis(tert-butylimido)bis(dimethylamido)tungsten (VI),tungsten hexacarbonyl, tungsten (VI) chloride,tris(N,N-bis(trimethylsilyl)amide)yttrium (III), yttrium (III) butoxide,diethylzinc, tetrakis(diethylamido)zirconium (IV),tetrakis(dimethylamido)zirconium (IV),tetrakis(ethylmethylamido)zirconium (IV), zirconium (IV) bromide,zirconium (IV) chloride, zirconium (IV) tert-butoxide, and a mixture ofany two or more thereof.